Xr650r Blowing Oil Out The Crankcase Vent

Discussion in 'Thumpers' started by XRider, Jun 12, 2009.

  1. XRider

    XRider Almost Lifelike

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    This one has me pretty stumped. I've got an XR650R that at high revs starts blowing oil out the crankcase vent. I know most of you are thinking it's over filled but it's not, it's got 1.75 qts. And it's not blowing out the counter shaft seal ether. The oil pump check valve has been replaced as well as the oil pump and the right side crank seal and the problem continues. The bike has a fresh Wiseco 11:1 piston but it had the problem before the top end was done. The only other thing I can think of is maybe the sump reed valve is broken.

    Have any of you guys seen this before? It only does it when the bike is taken on the freeway. It's the damnest thing. If anyone has any insight I'm all ears.:ear

    Thanks for any input guys.
    #1
  2. kenaroo

    kenaroo I am because i ride

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    Sorry... I'm drawing a blank.. cant think of anything.

    might want to post on thumpertalk if you haven't already.
    #2
  3. Trail Searcher

    Trail Searcher desert explorer

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    When did this start? Did you have a wiesco piston before this one. High crankcase pressure but why. What gearing are you using and with what wheels. I ride mine on the free way and it doesn't do this? Stock bore?
    Too much blow buy? Wonder if the piston to cylinder clearances are correct. I've got a known good used stock piston if you want to try it.
    #3
  4. Trail Searcher

    Trail Searcher desert explorer

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    What about a restiction of oil flow into the frame causing a high level in the crankcase. I always overthink this stuff.
    #4
  5. montesa_vr

    montesa_vr Legend in his own mind

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    Those really sound like the classic symptoms of too much oil. How do you know the engine and frame are empty when you add 1.75 fresh quarts?
    #5
  6. XRider

    XRider Almost Lifelike

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    You're right those are the classic symptoms of being over filled with oil. However, the frame and the crank case were drained, the oil pump removed, compressed air was blown into the oil system which evacuated any remaining oil. Oil pump was replaced with a new one then one qt of oil was poured into the engine and 3/4 qt was poured into the frame. So I can say with a fair amount of certainty that it's not over filled, in fact it's 1/2 pint low.

    For the guy asking about the piston, the clearance, taper, and out of round are all well within spec. The new top end didn't make a differance, it was still blowing oil after.

    Gearing is close to stock, 14/45 I think. When I wind it up on the freeway I'm not even close to hitting the rev limiter.

    I set up a little plastic catch bottle to see just how much oil is coming out of the engine. After a test run of 4.5 miles there was about 2-3 oz of oil in the bottle and the dipstick indicated the oil level was about 1 inch below the full line. This wouldn't seem to indicate that the oiling system is circulating the oil correctly. I tell you it's the damnest thing.

    Keep the ideas coming guys, at this point there's nothing that isn't worth considering and no stupid ideas. Thanks for the input.
    #6
  7. montesa_vr

    montesa_vr Legend in his own mind

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    OK, thank you, I'd agree we can scratch that off. Now back to Trail Searcher's question: when did this start? Gradually or suddenly? Did you ever own the bike when it didn't do this? Was there any change or event that preceded the oil problem?
    #7
  8. XRider

    XRider Almost Lifelike

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    I don't own the bike, it belongs to a customer. By the owners account it just simply started one day when he was out on a street ride. He wasn't pushing the bike beyond it's limits but he did say it was a very hot day. He claims he did not over heat it and from what I've seen I'd say that's probably true. I don't take a lot from the owners account because he doesn't give the bike much consideration so long as it starts. When he's done he leans it back up against the side of the house.

    The original oil that was in the bike was strained through a paint strainer and nothing strainge was in it.

    The only thing that I can think of is 1. The crank case is some how getting pressureized and pushing the oil out or 2. A piece of the main case that shields windage from the vent has for some reason broken away. That's why I was thinking maybe the reed valve was stuck open, that might cause to much possative crank case pressure. However, spliting the cases is the option of last resort, I'm hoping someone has seen this before.
    #8
  9. montesa_vr

    montesa_vr Legend in his own mind

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    OK, I'm wasting your time, you need somebody who knows something. Don't suppose any of the Honda Baja race team mechanics read ADVrider?

    I don't envy your situation -- you've put a lot of time in on this and have no answer for the bike's owner.

    I have seen this kind of thing on a small block Chevy engine once. The owner thought he had blown his engine because the oil level started dropping so fast. Turned out to be nothing more serious than a clogged PCV valve. Good luck.
    #9
  10. azcagiva

    azcagiva new orange flavor

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    Have you done a compression test yet? (I just recently got my 650r so I don't have much knowledge about them). In my experience I tend to over think this stuff and it turns out to be something simple.

    -John
    #10
  11. DualSport650

    DualSport650 Lucky Burglar

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    What about WORN RINGS letting blow-by down
    into the crankcase... adding too much pressure
    to the crankcase???

    :deal
    #11
  12. XRider

    XRider Almost Lifelike

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    #12
  13. XRider

    XRider Almost Lifelike

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    Compression is good, cylinder was bored, replated, and honed to final size. Did a leak down test also but the results were inconclusive.

    Dualspor650, the piston and rings a new.
    #13
  14. buddaxr650r

    buddaxr650r Adventurer

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    Has this started before or after you blew out the oil with compressed air? If after, maybe too much pressure built up and you have caused a leak in a seal somewhere.
    #14
  15. XRider

    XRider Almost Lifelike

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    It was blowing oil out the vent before I used the compressed air on it.

    I'm starting to think it's a failed o-ring on the oil passage that's right by the vent chamber. If you look at a picture of the inside of the main cases you'll see that next to the vent chamber there is an oil passage with an orifice and an o-ring. I'm thinking that o-ring failed so at high oil pressure/volume it's forcing oil into the vent chamber. I think it's the only way oil can get in there short of catastrophic failure of the main case.
    #15
  16. markk53

    markk53 jack of all trades...

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    I'm not sure where the breather is located, but is it possible that there is a missing baffle in the engine where the breather line exits. That could account for oil blowing out enmass.

    I had minor problems with my KLX blowing oil out into the air box, but it was not that bad and it was because the breather line ran down hill so any condensed oil went to the air box. Now I have an uphill routing with a sort of condenser tube to try to get a bit of the heavier mist to condense and flow back. No more drips, still blows off a bit of oil but not like that. The point is I know there's a metal baffle inside the cam cover where the breather exits. Without that, it might blow more oil out than ever.

    So, possibly run the breather up hill if it doesn't already. Maybe add a PVC tube stuffed with steel scrub pad stuff (my breather condenser tube idea) and something I've not tried, but KLR guys do, a PCV valve. They use one from some Mazda.

    That's all I got...
    #16
  17. jonpcovington

    jonpcovington Long timer

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    This may not solve your problem, but it did mine...

    When I was roadracing a 500 yamaha, I had removed the airbox and put a small K&N filter on a hose to the crank vent. It started blowing oil on my rear tire. The Yamahas had what is called an "oil labyrinth" in line between the breather and the airbox. It is made with an inverted cone inside to catch and return any oil blown out of the breather. I put this inline in the breather hose and it solved the problem. You could probably find one in a salvage yard, or maybe even order an NOS piece at a dealer. My Duke II doesn't have one, but I have seen several Hondas that do. including my TLR200.
    #17
  18. markoLT

    markoLT n00b

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    for me is the same problem- my adv 640 blows oil on my rear tyre and don't know the problem why does so. I thought maybe if I changed piston it will be all right, but when I read what you wrote, I'm confused now, no one knows the answer, very strange.
    #18
  19. markk53

    markk53 jack of all trades...

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    That was the function of my little breather condenser tube I wasn't aware of that Yamaha part. Is there a part number and is it an in-line thing? What 500? I don't recall anything like that on my SR.

    The breather tube I made was about a 3' long piece of 3/4 PVC capped on each end with two smaller diameter pieces (sized to fit the breather line hose) glued into holes drilled into the side of the caps and tube. I put some of that real coarse steel pot scrubber pad material in the tube before gluing up, figuring the oil mist would pass through and some of the denser mist would condense on the steel mech and flow back down hill to the cam cover. The tube is angled up slightly so as to aid in the flow back down.

    The stock breather line went from the cover immediately down to the air box so any condensed oil went to the air box and dripped out the bottom. After the installation of the breather tube my oil drip vanished.

    The big single still huffs off some oil through the air box when running mid/high rpm, but that's just a big single with the constant varying crank case pressure. I still want to try that Mazda PCV valve though.
    #19
  20. jonpcovington

    jonpcovington Long timer

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    I don't remember about the SR, but I know for sure it was on the XT and the TT.
    #20